Designing in Circles

Abstract: Round buildings are a popular—but sometimes expensively perceived—design choice. With careful engineering and planning, they can offer a creative, cost-competitive option. They add another element to a designer's aesthetic arsenal. The structural engineers at HTB Inc., Oklahoma City, have refined circular methods with recent work on five partially-round buildings. They do not begin with rectangular framing and force it into a circular shape; that would result in too many small structural pieces and an extremely complex geometry. Instead, they start with a truly circular plan—one with a sloping roof that forms a frustum, or segment, of a right circular cone. Architects say circular elements offer more flow and movement, and, consequently, more ways to use space inside and outside of a building. Obviously, a circular structure costs more than a rectangular one. The geometry involved is more complicated and requires slightly more tonnage for steel frame work. Contrary to popular perceptions, however, these extra costs are negligible. Round buildings are cost competitive with more conventionally-shaped structures.